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Biomedical subjects

M Ptok

Publications and source records attributed to M Ptok.

At least 73 records · Page 4Linked to original sources
PubMed1998

Supraglottal injection of botulinum toxin type A in adductor type spasmodic dysphonia with both intrinsic and extrinsic hyperfunction.

Patients with adductor type spasmodic dysphonia (SD) often exhibit both glottal and supraglottal hyperfunction. Based on the hypothesis that a "ventricular muscle" may contribute to the hyperfunction in these cases, eight patients with adductor type SD were treated with bilateral injection of botulinum toxin type A into the ventricular folds. Four weeks after injection, ventricular fold hyperfunction was absent in all cases. Number of voice breaks, standard deviation of fundamental frequency, and shimmer were significantly improved. Voice range profiles of the speaking voice were significantly extended in dynamic and frequency range. Side effects were a breathy phonation and mild swallowing difficulties without aspiration for about 1 week. Patients' self-rating concerning strangled and breathy voicing demonstrated an interval of acceptable voice quality between 1 week and 4 months after injection in all cases. Results suggest that supraglottal injection in patients with SD of both glottal and supraglottal hyperfunction, as a new approach, can normalize supraglottal activity and improve glottal voicing. Based on our experience with other patients with adductor type of SD, this injection technique is as efficient as injection into the thyroarytenoid muscle. Nevertheless, it remains to be proved that a pathologic ventricular muscle activity is addressed by this technique or if it is based on spreading to the thyroarytenoid muscle.

Acoustics↗
PubMed1997

[Transitory evoked and distortion products of otoacoustic emissions in absent auditory evoked potentials].

Transient click-evoked otoacoustic emissions (TEOAE) and distortion-product otoacoustic emissions (DPOAE) are produced by an active biomechanical process in the cochlea, presumably related to outer hair-cell activity. Although it is generally accepted that in most cases of hearing loss with absent auditory evoked potentials neither TEOAE nor DPOAE can be found, some cases with such a constellation have been described. Here we report another four cases of children with severe to profound hearing loss where we discovered reproducible TEOAE and DPAOE, whereas auditory evoked potentials were missing. TEOAE and DPOAE recordings in these cases indicate substantially preserved outer hair-cell function independent of profound pre-sensineural hearing loss. Since the incidence of children with preserved otoacoustic emissions together with impairment of synaptic or postsynaptic function of the first neuron is not known, the unconditioned use of TEOAE nor DPOAE as a screening instrument must be seriously questioned. Secondly, in conjunction with subjective audiometry and brain-stem-evoked potentials, emission recordings is an indispensable measurement prior to cochlear implantation and use of high-power hearing aids.

Acoustic Stimulation↗
PubMed1996

Neuronal networks and self-organizing maps: new computer techniques in the acoustic evaluation of the infant cry.

Neuronal networks are computer-based techniques for the evaluation and control of complex information systems and processes. So far, they have been used in engineering, telecommunications, artificial speech and speech recognition. A new approach in neuronal network is the self-organizing map (Kohonen map). In the phase of 'learning', the map adapts to the patterns of the primary signals. If, the phase of 'using the map', the input signal hits the field of the primary signals, it resembles them and is called a 'winner'. In our study, we recorded the cries of newborns and young infants using digital audio tape (DAT) and a high quality microphone. The cries were elicited by tactile stimuli wearing headphones. In 27 cases, delayed auditory feedback was presented to the children using a headphone and an additional three-head tape-recorder. Spectrographic characteristics of the cries were classified by 20-step bark spectra and then applied to the neuronal networks. It was possible to recognize similarities of different cries of the same children as well as interindividual differences, which are also audible to experienced listeners. Differences were obvious in profound hearing loss. We know much about the cries of both healthy and sick infants, but a reliable investigation regimen, which can be used for clinical routine purposes, has yet not been developed. If, in the future, it becomes possible to classify spectrographic characteristics automatically, even if they are not audible, neuronal networks may be helpful in the early diagnosis of infant diseases.

Acoustics↗
PubMed1996

Distribution of immunocompetent cells in various areas in the normal laryngeal mucosa of the rat.

The larynx can be divided into a supraglottic, a glottic and a subglottic area, each serving different functions. In many cases of laryngitis the site of infection is located in one area, leaving other areas unaffected. It seems reasonable to speculate that the underlying cause of the heterogeneous infection pattern in the larynx is the different processing of infectious agents. Therefore, the number and distribution of granulocytes, macrophages, dendritic cells, natural killer cells and T and B lymphocytes in the normal laryngeal mucosa of young rats were studied. The results show that, with the exception of granulocytes, all subpopulations were present in different numbers. Many macrophages and dendritic cells but only a few natural killer cells and T and B lymphocytes were located in the mucosa. Dendritic cells, natural killer cells and T and B lymphocytes were rarely present in the vocal fold area, whereas in the subglottic area they were present in high numbers. Thus, differences in the composition of immunocompetent cell populations between laryngeal areas were detectable.

Animals↗
PubMed1996

[Articulatory capacity and intelligibility of speech of patients with carcinomas of the mouth cavity. A comparison of pre- and postoperative results of various reconstruction techniques].

Radical orofacial tumor resections often result in speech and swallowing dysfunctions. Thus, both communication ability and life quality can be markedly impaired in patients. Dysfunction is mostly related to the amount of tissue removed and the reconstruction technique used. In this prospective study, pre- and postoperative speech intelligibility following reconstruction with either local grafts, free jejunal flaps or myocutaneous/fasciocutaneous flaps was examined by subjective assessment of monosyllables chosen from the Freiburg audiometry test ("reverse speech intelligibility test"). It was shown that linguodental affricates and dorsofaucal plosives were especially affected, even preoperatively, in patients with T3 and T4 tumors, while additional deterioration of speech function occurred postoperatively. When comparing reconstruction techniques, use of local grafts showed less postoperative deterioration in the patients with T3 and T4 tumors (expert rating/student rating -5.0% +/- (-3.8%), whereas impairment was much more evident when jejunal flaps (expert rating/student rating -27.9% +/- (-35.1%) and myocutaneous and faciocutaneous flaps (expert rating/student rating -34.2% +/- (-48.1%) were used. Results demonstrated that patients should be informed about negative side effects following radical tumor resections and reconstructions of large tissue defects. Surgery should avoid marked motor and sensory nerve lesions whenever possible. Before speech therapy is begun, speech function should be examined carefully. Speech intelligibility should also be documented, e.g. with audio tapes, for quality assessment.

Articulation Disorders↗
PubMed1996

[Reconstruction of speech and chewing function after extensive tumor resection in the area of the jaw and face].

BACKGROUND: Following extensive resections of head and neck tumors, re-establishing speech and masticatory function are of crucial importance for the patient. METHODS: In 23 patients with vascularised jejunal grafts for reconstruction of the intraoral mucosa, tongue and floor of mouth, a speech intelligibility test was performed, tongue and floor of mouth mobility was investigated using a 3.5 MHz ultrasound scanner. In another 18 patients with vascularised bone grafts for reconstruction of the mandible, masticatory function was analysed using a T-scan system and a miniature pressure transducer. RESULTS: Speech results with jejunal grafts in the lateral floor of mouth/tongue region may attain 91.4%, in anterior floor of mouth reconstructions 63.4%. Patients with implant-bone dentures and vascularised bone grafts prefer the non-reconstructed side for chewing. Masticatory force is significantly diminished compared to a control group. DISCUSSION: Lack of neurosensitive feedback mechanisms may be responsible for diminished chewing pressure and also for inferior speech results despite good floor-of-mouth/tongue mobility. CONCLUSIONS: Despite complex microvascular tissue reconstructions, severe functional impairments remain and necessitate further investigations on improvement of postoperative speech, swallowing and chewing function.

Adult↗
PubMed1996

Age dependency of the composition of immunocompetent cells and the expression of adhesion molecules in rat laryngeal mucosa.

Clinical evidence shows that laryngeal infections in infants differ significantly from those in adults. Therefore, the composition of the mucosal immune system (granulocytes, macrophages, dendritic cells, natural killer cells, and T and B lymphocytes) and the epithelial expression of class II-MHC molecules and adhesion molecules ICAM-1, VCAM-1, and E-selectin were studied in the larynx of newborn, 5-week-old, and 3-year-old rats. With the exception of macrophages, the immunocompetent cells began to immigrate into the laryngeal mucosa after birth, indicating that the laryngeal mucosa in newborn rats is immature. In contrast, ICAM-1 was already expressed. The number of immunocompetent cells and the expression of epithelial class II-MHC and ICAM-1 increased with age. Immunocompetent cells and epithelial class II-MHC and ICAM-1 expression were mainly detected in the subglottic region, but were almost absent in the vocal fold region.

Aging↗
PubMed1996

[Use of self-organizing neural networks (Kohonen maps) for classification of voice acoustic signals exemplified by the infant voice with and without time-delayed auditory feedback].

Subjective and auditory assessment of the voice is now more commonly being replaced by objective voice analysis. Because of the amount of data available from computer-aided voice analysis, subjective selection and interpretation of single data sets remain a matter of experience of the individual investigator. Since neuronal networks are widely used in telecommunication and speech recognition, we applied self-organizing Kohonen networks to classify voice patterns. In the phase of "learning," the Kohonen map is adapted to patterns of the primary signals obtained. If, in the phase of using the map, the input signal hits the field of the primary signals, it will resemble them closely. In this study, we recorded newborn and young infant cries using a DAT recorder and a high-quality microphone. The cries were elicited by wearing uncomfortable headphones ("cries of discomfort"). Spectrographic characteristics of the cries were classified by 20-step bark spectra and then applied to the neuronal networks. It was possible to recognize similarities of different cries of the same children and interindividual differences, as well as cries of children with profound hearing loss. In addition, delayed auditory feedback at 80 dB SL was presented to 27 children via headphone using a three-headed tape-recorder as a model for induced individual cry changes. However, it was not possible to classify short-term changes as in a delayed feedback procedure. Nevertheless, neuronal networks may be helpful as an additional tool in spectrographic voice analysis.

Acoustic Stimulation↗
PubMed1995

[The language and speech skills in 417 children with cleft formations].

Children with cleft palate often suffer from hearing, speech, and language articulation disorders. In order to design an efficient rehabilitation program for children thus affected, it is mandatory to acquire knowledge of the long term results achieved by the various therapeutical strategies including velopharyngoplasty and speech therapy. In this follow-up study 417 children with cleft palate (excluding isolated cleft lip) were examined in an interdisciplinary approach by maxillofacial surgeons, orthodontists, otolaryngologists, audiologists, and speech and language pathologists. The examinations determined that 93% of the children had speech or language disorders and 80% of these children suffered from mild to severe conductive hearing loss with or without clinical signs of otitis media with effusion. In 58 children (14%) with rhinolalia aperta, which had not been improved after one year of speech therapy, velopharyngoplasty with a cranial based pharyngeal flap was performed. The study showed that language skills do not correlate to the type of cleft palate, but rather to the frequency and degree of hearing loss. Using an interdisciplinary approach in early detection and the prompt clinical correction of cleft palate disorders resulted in only 49% of the affected children having to undergo speech and language therapy. In 51% of the affected children no speech therapy was necessary at all. The results presented in this study lead to the conclusion that our program for managing the rehabilitation of children with cleft palate is efficient.

Adolescent↗
PubMed1995

[Diagnosis of auditory threshold with frequency-specific recording of auditory evoked potentials: personal results and methodological aspects].

Results and Overview of Methods: Auditory brain stem responses are widely used in objective assessment of hearing function in both children and adults. Because of the lack of frequency specificity, several attempts were made to optimize responses using tone stimuli. Tone stimuli are characterized by intensity, frequency, and duration. Hence, there are important influences on the waveforms with respect to rise, plateau, and fall time. In addition, noise masking techniques are used to suppress both spectral sidebands of the stimulus and cochlear response not corresponding to the test frequency. In this paper, results on tone burst stimulation in notched noise masking are presented. Using this technique, reproducible waveforms (Jewett I to V resembling peaks) including a middle latency component could be obtained. Various stimulus characteristics (clicks, tone pips, tone bursts, Gaussian shaped stimuli), masking techniques (high-pass noise, notched noise), spectral characteristics, and time saving strategies are critically discussed.

Acoustic Stimulation↗
PubMed1995

[Results of recording frequency-specific acoustically evoked potentials with masked stimuli].

This study presents results of frequency-specific brainstem-evoked response audiometry using tone bursts in ipsilaterally notched noise. The technique used was described by Picton in 1979. Sixty-four children and adults were examined using this method. Differences between pure-tone behavioral thresholds and notched noise thresholds were calculated in 15 patients. Mean differences ranged from 1-3 dB and standard deviations from 8-17 dB for frequencies tested at 500, 1000, 2000 and 4000 Hz. Differences in 12 children were calculated for thresholds obtained in a free-sound field. Maximum mean differences were 12 dB and standard deviations +/- 8 dB. These findings show that accurate frequency-specific thresholds can be obtained with brainstem-evoked response audiometry using tone bursts in notched noise.

Adolescent↗
PubMed1995

[Function and morphology of the larynx of the domestic guinea pig. An animal model for laryngologic and phoniatric research?].

The present study was undertaken to collect data on fundamental functional and morphological features of the guinea pig larynx using frequency analysis of animal vocalizations and light and scanning electron microscopy. Vocalizations of healthy animals were recorded in an anechoic chamber and were analyzed with short-time fourier transformation (color spectrograms). From the multitude of vocalization patterns produced by the guinea pig, distress squeals were selected as a typical, reproducible, voiced sound. These were stereotyped, upward-frequency modulated, multiharmonic signals with a formant-like structure. The fundamental frequency of this sound rose by about 1.5 octaves and reached up to 6 kHz near the end of the call. The different regions of the endolaryngeal epithelia showed morphological properties that corresponded to proposed functional significance. Keratinized squamous epithelium covered the supraglottic region. The marginal rim of the vocal cord was covered by a very thin epithelium with very flat cells covered with short microvilli. The subepithelial space was filled with loose connective tissue. The subglottic region was covered by respiratory epithelia. Based on these findings, we propose that the larynx of the guinea pig can be used as a model in phoniatric and laryngological research.

Animals↗
PubMed1994

[Drug therapy of acute inner ear hearing loss in childhood and adolescence].

Sensorineural hearing loss in early childhood may severely interfere with normal speech and language development. This by itself requires pursuit of an effective therapeutic procedure. Here we report the results of therapy with a rheological agent and procaine-HCl with or without the addition of steroids. Immunological testing was also studied for possible circulating antibodies in sera of affected children. Retrospective analysis of therapeutic results showed that the therapeutic procedure employed may be beneficial, since hearing improved considerably in some cases. Since an autoimmune-related sensorineural hearing loss has been postulated for some years, results presented here could be used as an argument for the presence of antibody-related inner ear disorders in early childhood. These findings suggest that circulating antibodies in children suffering from sensorineural hearing losses produce an inflammatory process involving inner ear structures. Circulating antibodies may also indicate a secondary immune reaction. However, sensory hearing loss occurring in early childhood may be steroid sensitive.

Adolescent↗